This invention relates generally to gas generation, production or supply such as used for or in association with the inflation of inflatable devices such as inflatable vehicle occupant restraint airbag cushions used in vehicular inflatable restraint systems. More particularly, the invention relates to inflation systems such as for use in providing a supply of inflation medium to an inflatable restraint element and related methods of operation which employ or utilize magnetic characteristics of gases.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an “airbag,” that is inflated or expanded with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. In such systems, an airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, the cushion begins to be inflated in a matter of no more than a few milliseconds with gas produced or supplied by a device commonly referred to as an “inflator.”
Many types of inflator devices have been disclosed in the art for use in inflating one or more inflatable restraint system airbag cushions. Many prior art inflator devices include a solid form of gas generant material which reacts to produce or form gas used in the inflation of an associated airbag cushion.
A common form or type of prior art inflator device includes a gas generant material in a solid form and which solid gas generant material is caused to react to produce or form gas used in the inflation of an associated airbag cushion. For example, such inflators can generally produce or derive inflation gas via the combustion of a solid form gas generating material, i.e., a pyrotechnic. In practice, the combustion of such gas generating materials can typically also produce various undesirable combustion products, including various solid particulate materials. The removal of such solid particulate materials, such as by the incorporation of various filtering devices within or about the inflator, can undesirably increase inflator design and processing complexity as well as the costs associated with such inflator devices and associated processing. In addition, the temperature of the gases emitted from such inflator devices can typically vary between about 500° F. (260° C.) and about 1200° F. (649° C.), dependent upon numerous interrelated factors including the desired level of inflator performance, as well as the type and amount of gas generant material. Consequently, airbag cushions used in conjunction with such inflator devices are commonly constructed of or coated with special materials such as to desirably be resistant to such high temperatures. As will be appreciated, such specially fabricated or prepared airbag cushions are typically more costly to manufacture and produce.
Another category of inflator devices disclosed in the art for the inflation of one or more inflatable restraint system airbag cushions is often referred to as “compressed gas inflators.” This category of inflator devices generally refers to those inflator devices which contain a selected quantity of compressed gas. For example, one particular type of compressed gas inflator, commonly referred to as a “stored gas inflator,” simply contains a quantity of a stored compressed gas which is selectively released to inflate an associated airbag cushion. A second type of compressed gas inflator, commonly referred to as a “hybrid inflator,” typically supplies or provides inflation gas as a result of combining a stored compressed gas with the combustion products resulting from the combustion of a gas generating material, e.g., a pyrotechnic.
In the past, compressed gas inflators of various types have commonly been at a disadvantage, as compared to pyrotechnic inflators, in terms of size, weight and/or cost. This is especially significant in view of the general design direction toward relatively small, lightweight and economical modem vehicle components and assemblies. Thus, there is a continuing need and demand for further improved apparatus and techniques for inflating inflatable devices such as inflatable airbag cushions.
A more recently developed type of inflator device is at least in part the subject of commonly assigned Rink, U.S. Pat. No. 5,669,629, issued 23 Sep. 1997; Rink et al., U.S. Pat. No. 5,884,938, issued 23 Mar. 1999; and Rink et al., U.S. Pat. No. 5,941,562, issued 24 Aug. 1999, the disclosures of which patents are hereby and expressly incorporated herein in their entirety. In one form of such recently developed inflator device, inflation gas is produced or formed, at least in part, via the decomposition or dissociation of a selected gas source material, such as in the form of a compressed gas and such as via the input of heat from an associated heat source supply or device. Such an inflator device is sometimes referred to as a “dissociative inflator.”
In view of possibly varying operating conditions and, in turn, possibly varying desired performance characteristics, there is a need and a desire to provide what has been generally termed or referred to as an “adaptive” inflator device and a corresponding inflatable restraint system. With an adaptive inflator device, output parameters such as one or more of the quantity, supply, and rate of supply (e.g., mass flow rate) of inflation gas, for example, can be selectively and appropriately varied dependent on one or more selected operating condition such as ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.
Perhaps one of the simplest forms of a prior art adaptive inflation system is an inflation system which utilizes an inflator which provides two levels or stages of performance, e.g., commonly called or referred to as a “two-stage” or “dual stage” inflator. Various proposed or currently available dual stage inflator devices appear to be based on the principal of packaging together two separate inflators. As a result, such inflator combinations commonly include two distinct pressure vessels, two sets of filter or inflation gas treatment components, e.g., one for the output of each of the pressure vessels, and two distinct diffusers, again one for the output of each of the pressure vessels. Thus, it has been difficult to provide an adaptive inflator which will satisfactorily meet the size, cost and weight limitations associated with modern vehicle design, particularly as it pertains to driver side applications. Moreover, those skilled in the art will appreciate that even such a relatively simple two-stage inflator may require significantly sophisticated actuation and/or control systems, as compared to typical single stage inflators, in order to realize particularly desired adaptive performance capabilities.
Commonly assigned Rink et al., U.S. Pat. No. 5,941,562, issued 24 Aug. 1999 discloses an improved adaptive output inflator wherein inflator performance, such as measured by inflator gas output, can be appropriately varied and selected by appropriately varying and selecting the operational oxidant composition of the inflator.
While the devices and methods disclosed therein have in general at least in part been successful in satisfying the need and demand for improved adaptive output inflators and methods of inflation, there remains a continuing need and demand for further improved inflation systems and methods of operation such as may improve one or more of the safety, simplicity, effectiveness, economy, and reliability thereof, particularly as applied to adaptive inflation systems and operation.